Effects of Alpha-lactalbumin Intake on Metabolic and Cognitive Functions in Elderly

September 26, 2025 updated by: Marielle PKJ Engelen, PhD, Texas A&M University

Effects of Alpha-lactalbumin on Metabolic and Cognitive Functions in Healthy Older Adults

Aging modifies the metabolic pathway of the neurotransmitter serotonin by reducing the synthesis rate and increasing the breakdown rate of serotonin, possibly related to the observed enhanced sensitivity of the serotonergic pathway. Since serotonin plays a prominent role in neuropsychological functions such as anxiety, mood and memory, the enhanced sensitivity of the serotonergic pathway in aging can probably explain the fact that elderly are more vulnerable to develop cognitive deficits and depressive symptoms.

Serotonin synthesis in brain is regulated by its precursor tryptophan (TRP). Because tryptophan is an essential amino acid, modifying the availability of tryptophan through dietary intake, can directly influence central serotonin metabolism and consequently affective and cognitive processes.

The aim of this study is to test the hypothesis that an acute intake of whey protein with high levels of TRP such as alpha-lactalbumin can stabilize the metabolism of serotonin and subsequently enhance metabolic and cognitive functions in healthy older adults. The acute effects of this dietary protein will be investigated in subjects with mild cognitive impairment (MCI), or dementia, compared to control subjects in order to examine whether healthy older subject with MCI benefit more from the intake of alpha-lactalbumin and/or whey. The investigators will investigate if this meal can optimize serotonin metabolism by elevating plasma TRP levels and plasma TRP appearance and enhance splanchnic TRP extraction. In addition, the effects on mood and cognitive functions will be examined.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The study involves for all subjects 3 test days (approximately 8 hours each). On this test day the investigators will examine the acute effects of a protein meal. Subjects will receive a mixture of alpha-lactalbumin and/or whey and/or casein, carbohydrates and amino acid stable isotopes to investigate protein and amino acid kinetics (assigned to alpha-lactalbumin or whey or casein group on test day 1, then switch on test day 2 and 3). The subjects will receive these stable isotopes by infusion in their blood and by oral intake (e.g. simultaneously with protein meal). For study purposes, blood will be drawn approx. 25 times during 8 hours on the test day, altogether about 100-120 ml of blood will be drawn on the test day.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
59

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Texas
      • College Station, Texas, United States, 77843
        • Texas A&M University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

51 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion criteria subjects with dementia:

  • Dementia diagnosis
  • Ability to walk, sit down and stand up independently
  • Age 55 years or older
  • Ability to lie in supine or elevated position for 8 hours
  • Willingness and ability to comply with the protocol, including:

Adhering to fasting state from 10 pm ± 2h onwards the day prior to each study visit

Inclusion criteria healthy subjects:

  • Healthy male or female according to the investigator's or appointed staff's judgment
  • Ability to walk, sit down and stand up independently
  • Age 55 years or older
  • Ability to lie in supine or elevated position for 8 hours
  • Willingness and ability to comply with the protocol, including:

Adhering to fasting state from 10 pm ± 2h onwards the day prior to each study visit

Exclusion Criteria:

  • Any condition that may interfere with the definition 'healthy subject' according to the investigator's judgment (for healthy control group only)
  • Failure to give informed consent or Investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements
  • Indication of severe cognitive impairment (MOCA score < 17)
  • Established diagnosis of Insulin Dependent Diabetes Mellitus
  • History of untreated metabolic disease(s) including hepatic or renal disorder
  • Presence of acute illness or metabolically unstable chronic illness
  • Presence of fever within the last 3 days
  • Preplanned surgery of procedures that would interfere with the conduct of the study
  • Any other condition according to the PI or study physician that would interfere with proper conduct of the study / safety of the patient
  • Current alcohol or drug abuse
  • Known allergy to milk or milk products
  • Use of long-term oral corticosteroids or short course of oral corticosteroids 4 weeks preceding first test day
  • Use of protein or amino acid containing nutritional supplements within 5 days of test day
  • (Possible) pregnancy
  • BMI of < 18.5 or ≥ 40 kg/m2
  • Dietary or lifestyle characteristics: When during the period from enrollment to completion of the study (end of test day) any condition is developed, whether causing the subject to not meet inclusion criteria or to meet exclusion criteria, the subject will be excluded from the study

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Supportive Care
  • Allocation: Non-Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Healthy
healthy control subjects
Dietary supplement: Alpha-lactalbumin
Subjects will ingest the liquid meal containing alpha-lactalbumin and carbohydrates (0.6 g/kg FFM protein + 0.3 g/kg FFM carbohydrates).
Dietary supplement: Whey
commercially available whey protein
Dietary supplement: Casein
commercially available casein protein
Experimental: MCI
mild cognitive impariments
Dietary supplement: Alpha-lactalbumin
Subjects will ingest the liquid meal containing alpha-lactalbumin and carbohydrates (0.6 g/kg FFM protein + 0.3 g/kg FFM carbohydrates).
Dietary supplement: Whey
commercially available whey protein
Dietary supplement: Casein
commercially available casein protein
Experimental: Dementia
established diagnosis of dementia
Dietary supplement: Alpha-lactalbumin
Subjects will ingest the liquid meal containing alpha-lactalbumin and carbohydrates (0.6 g/kg FFM protein + 0.3 g/kg FFM carbohydrates).
Dietary supplement: Whey
commercially available whey protein
Dietary supplement: Casein
commercially available casein protein

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Net whole-body protein synthesis
Time Frame: 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal
Change in whole-body protein synthesis rate after intake of meal
0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Whole body collagen breakdown rate
Time Frame: Postabsorptive state during 3 hours
Hydroxyproline enrichment in plasma
Postabsorptive state during 3 hours
Citrulline rate of appearance
Time Frame: Postabsorptive state during 2 hours
Plasma enrichment of citrulline
Postabsorptive state during 2 hours
Skeletal and respiratory muscle strength
Time Frame: 1 day
Difference in leg strength and fatigue, handgrip strength and fatigue, and inspiratory and expiratory pressure between older adults with and without MCI.
1 day
Cognitive function and mood
Time Frame: Postabsorptive state during 3 hours and change after feeding
Outcome of neuro-psychological tests in healthy older adults with and without MCI in relation to the tryptophan metabolism
Postabsorptive state during 3 hours and change after feeding
Protein digestion after feeding
Time Frame: 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal
Ratio enrichment free phenylalanine versus phenylalanine from protein spirulina
0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal
Arginine turnover rate
Time Frame: Postabsorptive state during 3 hours
Arginine enrichment in plasma
Postabsorptive state during 3 hours
Tryptophan turnover rate
Time Frame: Postabsorptive state during 3 hours and change after feeding
Tryptophan enrichment in plasma in postabsorptive state and after intake of meal
Postabsorptive state during 3 hours and change after feeding
Insulin response to feeding
Time Frame: During 3 hours after feeding
Acute change from postabsorptive state after intake of meal
During 3 hours after feeding
Fat-free mass
Time Frame: Postabsorptive state during 15 min
Characteristics of study subjects
Postabsorptive state during 15 min
Myofibrillar protein breakdown rate
Time Frame: 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal
3methylhistidine enrichment in plasma
0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210 min post-meal
Glycine rate of appearance
Time Frame: Postabsorptive state during 3 hours
Glycine enrichment in plasma
Postabsorptive state during 3 hours
Taurine turnover rate
Time Frame: Postabsorptive state during 3 hours
Enrichment of taurine in plasma
Postabsorptive state during 3 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Texas A&M University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Marielle P Engelen, PhD, Texas A&M University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
April 2, 2014

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2016

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2016

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 6, 2014

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 7, 2014

First Posted (Estimated)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 10, 2014

Study Record Updates

Last Update Posted (Estimated)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 30, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 26, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2014-0065

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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